This invention relates to a circuit for controlling a rice cooker, and, more particularly, to a power interrupt countermeasure in a circuit for controlling a rice cooking operation by a processor such as a microcomputer.
A rice cooker which controls a rice cooking operation using a microcomputer has recently been developed. In general, the control circuit of such a rice cooker has three or more rice cooking modes, each using a different heating calorie, amount and e.g., high, medium and low heating calories for a rice cooking heater; and a desired rice cooking mode can be executed in accordance with user selection. More specifically, in addition to the HAKUMAI DAKI (polished rice cooking) mode which is most frequently used, there are provided a GENMAI DAKI (unpolished rice cooking) mode, a TAKIKOMI OKOWA DAKI (rice with other ingredients added or rice with red beans cooking) mode, and an OKAYU DAKI (rice gruel cooking) mode. Of these modes, the rice cooking heater is energized at the highest heating calorie in the polished rice cooking mode until rice cooking is completed. In the unpolished rice cooking, rice with other ingredients or rice with red beans cooking modes, the heater is energized at a medium heating calorie for a relatively long period of time. In the rice gruel cooking mode, the heater is energized at a low heating calorie for a relatively long period of time.
In the control circuit of the rice cooker, data indicative of the rice cooking mode selected by a user before operation is fetched by a processor, and the rice cooking operation is controlled in accordance with the fetched data.
In this case, if power interrupt occurs after setting the rice cooking mode, the preset rice cooking mode data may be lost due to a power interruption when the rice cooking operation is restarted.
For this reason, in the control circuit of a conventional rice cooker, when the cooker resumes operation after a power interrupt, the polished rice cooking mode, which is most frequently used, is automatically set and the rice cooking operation automatically restarted.
In the control circuit of the conventional rice cooker, as long as the polished rice cooking mode is preset in the case of power interrupt, no problem occurs. However, if another rice cooking mode is preset, various problems occur. That is, when the rice gruel cooking mode is preset, the rice gruel is abruptly cooked at too high a heating calorie and an overcooked state occurs. Similarly, when the unpolished rice cooking mode is preset, undercooking results since the unpolished rice is undesirably cooked for too short a time at a high heating calorie ordinarily suited to cooking polished rice within a short period of time. Therefore, it is difficult to perform appropriate cooking of rice other than polished rice.